Tile-boundary artifact reduction using odd tile size and the low-pass first convention.

It is well known that tile-boundary artifacts occur in wavelet-based lossy image coding. However, until now, their cause has not been understood well. In this paper, we show that boundary artifacts are an inescapable consequence of the usual methods used to choose tile size and the type of symmetric extension employed in a wavelet-based image decomposition system. This paper presents a novel method for reducing these tile-boundary artifacts. The method employs odd tile sizes (2N + 1 samples) rather than the conventional even tile sizes (2N samples). It is shown that, for the same bit rate, an image compressed using an odd tile length low-pass first (OTLPF) convention has significantly less boundary artifacts than an image compressed using even tile sizes. The OTLPF convention can also be incorporated into the JPEG 2000 image compression algorithm using extensions defined in Part 2 of this standard.     

TiB2和SiCW对Al2O3陶瓷材料高温摩擦磨损特性的影响

研究了Ａｌ２Ｏ３、Ａｌ２ｏ３／ＴｉＢ２和Ａｌ２Ｏ３／ＴｉＢ２／ＳｉＣＷ三处陶瓷材料在不同条件下的擦靡损特性。结果表明：三种陶瓷材料与硬质合金摩擦副的摩擦系数随温度温度的增加有不同的变化规律，摩擦表面的Ｘ射线衍射分析表明，摩擦系数的变化与陶瓷物膜的和结构有关，在高温下Ａｌ２Ｏ３／ＴｉＢ２陶瓷材料摩擦表面形成了具有优良的高温润性的ＴｉＯ２氧化膜，因而ＴｉＢ２的加入明显改善了Ａｌ２Ｏ３陶瓷材料 摩擦磨损     

DG抗高温隔离液在古深1井的应用

古深1井是大庆油田在古龙地区的一口风险探井,设计井深5 500 m,实际完钻井深为4 739 m。钻进过程中,多次出现塌、漏、卡等事故,造成井径不规则。为平衡压力,压稳地层,更好地隔离钻井液和水泥浆,提高顶替效率,设计采用DG抗高温隔离液。DG抗高温隔离液抗高温可达150℃,密度调节范围宽,抗高温悬浮稳定性好,失水量少,与水泥浆和钻井液相容性好。古深1井采用双级注水泥工艺,固井施工过程十分顺利,隔离液密度均匀,泵送容易,无发泡现象。从声幅测井情况来看,水泥面上部与隔离液交界处界面清楚,水泥环胶结良好,水泥返高达到了设计要求,混浆过渡段短,固井质量合格。     

Packet acquisition in upstream transmission of the DOCSIS standard

In upstream transmission of the DOCSIS (data over cable service interface specification) 1.0/1.1 and the TDMA mode of DOCSIS 2.0 standard, a packet begins with a preamble, the length and value of which are programmable by the headend. The acquisition process includes packet detection, symbol timing estimation, carrier frequency offset estimation and carrier phase estimation by means of the preamble so that the following information packet can be correctly demodulated. Methods to solve these tasks are not subject to standardization and are left to the system designer. However, they have a great impact on the system performance and thus are key elements for implementation. We present dedicated algorithms. A specific preamble is created and the corresponding scheme for packet acquisition is described in some detail. The packet detecting algorithm is independent of the carrier and symbol timing. The symbol timing estimate is obtained by using the minimum mean square algorithm regardless of the carrier frequency deviation and carrier phase. Algorithms for estimating the carrier frequency offset and carrier phase are proposed. Computer simulation results are given for all algorithms presented.     

模具采购管理工作浅谈

针对模具制造企业的特点，从采购管理概述、供应商质量控制、采购价格、供应商交货控制及付款方式简述了采购的管理工作。     

YAG：Nd激光照射犬气管粘膜的实验研究

An experimental study for the pathologic changes of the canine tracheal mucosa under YAG:Nd laser ablation was performed in order to master the appropriate parameters for the clinical treatment of YAG:Nd laser. 6 male and female Mongolia dogs weighing 13-18 kg were received 20W YAG:Nd laser treatment and their pathologic changes were examined instantly and 3, 7, 14 and 28 days after ablation.     

Seismic Physical Modeling Technology and Its Applications

1. Introduction Seismic physical modeling technology is an important method for the research on seismic exploration theory and methods. In seismic physical experiments, the earth, mantle or field site are scaled down to physical models according to the similarity principle, and then the seismic field and its variation are observed in the laboratory for the research work on the theories and methods of the earth structure, earthquake forecasting, energy and mineral resource exploration, and engi…     

A new efficient numerical method and the dynamic analysis of composite laminates with piezoelectric layers

Firstly, a numerical method for the inversion of Laplace transform is developed and its accuracy is shown through examples. Then, a state-vector equation for the dynamic problems of piezoelectric plates is deduced directly from a modified mixed variational principle for piezoelectric bodies and its exact solution for the dynamic problems of simply supported rectangle piezoelectric plate is simply given. For multilayered hybrid plates, we derive the solution in terms of the propagator matrices. The techniques accounts for the compatibility of generalized displacements and generalized stresses on the interface both the elastic layers and piezoelectric layers, and the transverse shear deformation and the rotary inertia of laminate are also considered in the global algebraic equation of structure. Meanwhile, there is no restriction on the thickness and the number of layers. As an application of the numerical inversion of Laplace transform presented in this paper, typical numerical examples of the harmonic vibration and transient response are proposed and discussed. Since the highly accurate numerical results, they can serve as benchmarks to test various thick plate theories and various numerical methods, such as the finite and boundary element methods for transient response problems.     

武钢钢铁产品创新的战略思考

产品创新是企业生存和发展的基础。分析了武钢钢铁产品的市场需求，找出了武钢企业外部环境的机会与威胁和企业内部的优势与劣势，提出了产品创新的战略措施。     

Al2O3/TiB2/SiCw三元复合材料的力学性能及显微结构

以Al₂O₃为基体,SiC晶须和TiB₂颗粒两种增韧剂,采用热压烧结工艺制备了Al₂O₃/TiB₂/SiC_w三元复合陶瓷材料。研究了热压工艺参数对材料致密度的影响和晶须含量对该复合材料的力学性能和显微结构的影响。结果表明;随晶须含量的增加,该复合材料的热压温度和保温时间需要相应的增加;晶须拔出、裂纹偏转和晶须的桥接为该复合材料的主要增韧机理;随晶须含量的增加,该材料的室温断裂韧性增加;该材料的断裂韧性随温度的升高而呈增大趋势,并且晶须含量越高,材料的高温断裂韧性增幅越大。